Project Summary/Abstract. Manipulating stem cells offers one of the most promising treatments for a number of brain disorders. Potentially, one of these disorders is alcohol and substance abuse. Chronic alcohol abuse is one of the greatest health care problems among veterans. In particular, alcohol abuse can cause learning and memory loss and brain dysfunction, e.g., dementia and Korsakoff's Syndrome, and it is a co-morbid factor in many diseases including mental disorders and hepatoencephalopathy. A major contributor to learning and memory is the production of neural stem cells (NSCs) and their fate (e.g., neuron or glia) of their progeny. In the adolescent and adult, this production is largely restricted to cerebral cortex, and particularly, the dentate gyrus. The environment of a NSC defines its proliferative activity and capability. One class of proteins that comprises the NSC niche is growth factors. One such unique protein is transforming growth factor (TGF) 1;it plays the $ critical function of moving cells out of the cycling population. Interestingly, NSC production and TGF1expression decline with age. Ethanol can affect cell proliferation and cell fate decisions, and in the $ developing brain, it appears to act through TGF1. The present study will test the hypothesis that ethanol alters $ neuronogenesis through its effects on TGF1. $ The proposed project constitutes a series of three complementary studies designed to examine mechanisms through which ethanol can affect NSC activity. (1) Learning and memory depend upon the production of new neurons in the dentate gyrus of the hippocampal formation. We will use organotypic cultures to determine the effects of ethanol (a) on the proliferation of NSCs in the dentate gyrus, (b) on the survival of these NSCs, and (c) on the activation of TGF1 systems expressed by these NSCs. (2) Lines of $ NSCs derived from forebrain NSCs will be used to explore the effects of ethanol on TGF1-regulated cell $ proliferation and fate decisions. In addition, we will identify genes that are up- and down-regulated and are silenced (methylated) by ethanol and/or TGF1. (3) NSCs will be transplanted to determine the effects of $ ethanol and/or TGF1 on genetic and environmental contributions to determining cycling behavior and to $ defining cell fate. These studies will use a multidisciplinary approach (molecular biology, anatomical, and biochemical methods) to examine complementary model systems. Aims 1 and 3 will examine age-dependent changes by examining adolescents and adults in order to determine further if TGF1 is a target of ethanol. $ As a unit, the proposed studies will assess mechanisms that underlie alcohol-induced dementia. Furthermore, they will provide (a) the basis for ameliorating alcohol-induced defects and (b) valuable new data on the organization of neurotrophin systems in the normal brain.